Telephony.



G. d. GUMMNGS.

TELEPHONY.

APPLIOATION FILED ooT.14, 1909.

'Patented July 11, 1911;

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nin ax` .arr onirica GrEQRCvrEI C. GUMIVIINGS, OF WESTERN SPRINGS, ILLINOIS.'

TELEPHONY. l

-To LZZ 'whomit may concer/n:

. cise, and exact description, reference being had' to the accompanying drawings, forming a part of this speciication.

My invention relates to telephony, arid/has for its object the provision'of an improved system that is especiallyy adapted to the tele phonic connection of substations witha central office and in which the apparatus and circuit arrangements are simplified and; at the same time well adapted to the various operations of the system.

The system of my invention is well adapted to that class of service in which the substations may call the central ohice, and the central oiiice may call the substations, but in which the substations may not call each other. 4 l

The accompanying drawing illustrates one practical embodiment of my invention,-

the line and substation apparatus and the j central station apparatus being diagrammatically shown. L

In the system illustrated I have shown but three telephone lines extending from substations A B C to the central office I),

but it is to oe understood that I do not limit myself to the .number of such lines. The telephone lines are preferably metallic, one

,side of each preferably terminating at the corresponding substation in a pair of multiply related contacts 6,'0, while the'companion side terminates in a switch spring a.

.Thenormal contact?) is connected withwits side of the telephone line through a condenser d, and the alternate contact c is conf` nected with said side of the telephone line through the corresponding substation trans-Y mitting telephone e.

The position of the .springe is governed by the switch hook f in such a manner that when said switch hook occupies the position to which it is switch a engages its alternate contact c.

Each telephoneline terminates at the central ofce in af pair of switches or key Specification of Letters Patent.

Application led October 14,1909.

Patented duly Il, lgll..

Serial No. 522,588.

springs Z1, which have normal contacts that are connected withswitches or key springs The normal contacts of the springs Z con-- stitute the terminals of circuit connections that include a battery Z3 ,that is common to all of the `lines and line magnets or relays Z that are individual to the lines. Though" the battery c is thus normally connected with all of 'the lines, the flow of current therefrom over the telephone lines is normally prevented by the condensers Z that are normally in serial relatiorrwith the sides of their associate lines by way of the normal contacts that are engaged with the switches a when said switches are moved by, the associate switch hooks when supporting' telephone receivers. `When a party at a telephone substation desires to communicate with the central ofhce, such party remorts his telephone receiver g from its swcij'ych hook f, thereby to exclude the associate fndenser CZ from circuit and to include `fthe telephone transmitter c in circuit, said titansmitter being included in ametallically'continuous conductor that metallically unites the two sides of the calling` telephone line, thereby to afford a. closed circuit for the battery Z: and the line magnet Z of the calling line. This magnet is consequently energized thereby occasioning the presentation of a line signal. In the preferred embodiment of the invention the magnet Z does not direct-ly present the line signal, but is used merely' as a relay to close a local signaling circuit including a line signal lamp m,fthe battery c andan armature switch n, the Signal thereby occasioned being a visual signal. I also provide means for creating an audible signal, which means is desirably common to all of the lines and is desirablybrought into operation by any actuated relay Z. The

magnet o that opens and closes the conductor 79 that includes it in circuit, this conductor being connected at one en d with one side of the battery 7;', and having connection atv its other end with the multiply con nected contacts g provided for the switches r that are connected with the other side of the battery 7c and which are governed by the relays Z. When, therefore, any line is callr ing, the visual signal at fm, is accompanied' by an audible signal produced at the come -mon source o, the magnet o Aoperating as a buzzer. tion fails to notice tlievisual calling signal If the attendant at the central sta' displayed by the `line-lamp m belonging to lever s belonging to the terminals 71, of the s engaging their a calling substation, the audible signal should attract his attention.

Theattendant at the central station will, in response to the line signal, move the key calling line to a position where such terminalswill be separated from their normal contacts, thereby to exclude the signaling apparatus Z, m, o, from, association with the calling line, the line terminals z, consequently alternate contacts that constitute terminals of aconducting element that includes the telephone outfit t, belong-- ing. to the central station, and the common battery, the terminals 7L of the calling line thus` being, connected with each other through said ;telephone apparatus t and the common battery k, said common battery thereby'. supplying the central station Yand 'the calling substation transmitters with operating current.

. I f the central station attendant desires to signala substation, key lever s belonging to a selected line is thrown to that position 11i which a source' of signaling current is connected in circuit with the called line. In the embodiment of the invention illustrated,

- the alternate contacts of the key springs constitute the terminals of a secondary or induced coil u, which is looped in the called line when said springs e' engage their said alternate contacts. The primary or inducing coil 'u is atthis time included serially in circuit with the circuit making and break- 'ing .armature switch of the magnet 0 and the winding of said magnet, this circuit being traceable from the battery la through the -magnet o. and its said armature switch, the

primary or inducing winding fu, the alter- -nate contact ot' the left hand key spring i individual to the called line, the contact w then engaged by said alternate contact, thence back to said batt-ery.

ns a consequenceI of the closure ot' thecircuit just traced, current through the inducing or pri- "mai'y -coil is rapidly interrupted, whereby a suitable signaling current is impressed upon the secondary or induced coil u that will operate the signal receiver at the selected station. Vhen the called station responds,

the operator at the central station will' 'i throw the actuated key lever s to its extreme way of the'springs h. of the first key and their normal contacts, the springs of Said key and their normal contacts, the alternate contacts of the springs i of the second switch and the springs 71, of the second switch to-4 gether with their normal contacts. f An important feature of my presentinvention resides in the elimination of vthe commonly employed signal receiver and proyiding such a circuit relation'and equipmei-itjin the common battery system, that thetelephone receivers g at a called station may also constitute a lsignal receiver. This, feature of my invention is realized by causing' the telephone receiver g to be connected with the sides of their associated telephone lines through their associate 'condensers d when said receivers are upon their switch hooks, said condensers normally preventing the How of battery current overthe lines, while permitting the passage of wave form signaling current from some suitable source',as the secondary u, over any line called, and through the telephone receiver g of the called line-whosediaphragm is thereupon vibrated with suiiicient rapidity by the wave form signalin currentas to cause an audible signal. l' hen any substation desires to signal the central station, thetelephone transmitter e at the calling station is substituted for the condenser thereatin the manner and ',wit-h the results that have been specied.

While I have herein shown and particu-l larly described the preferred embodiment of` my invention, I donot wishto be limited` to the precise details of construction andA circuit arrangement illustrated, but

Having thus described my invention, I

claim as new and desire to secure by LettersPatent the following:

1. A telephone system including Va plurality of telephone lines extending from substations to a central oflice, telephone receivers, telephone transmitters, switch hooks and condensers at the substations, switching devices at thesubstations operated by the switch hooks when moved by the telephone receivers when placed thereon to cut the condensers into serial relation with the, telephone receivers and the telephone lines, and serving to includev the telephone transmitters in serial relation with the-sides of the' telephone lines and telephone receivers to the exclusion of the condensers wheny the telephone receivers are removedfrom their switch hooks,whereby direct current may flow through the telephone receivers and transmitters, line signal devices at the central office individual to said telephone lines, a source of direct current, said line signal devices and source of direct current being normally connected with the telephone `lines to enable the closure of their circuits when the telephone receivers are removed from their switch hooks, means at the central office for impressing signaling current upon the telephone lines that is adapted to tind passage through the condensers and which is capable of operating the telephone receivers at the substations as signal receivers, and switching devices lat the central oiiice that are individual to the telephone lines for including the telephone transmitter at the central oiiice in circuit With said source of direct current and serving when thus op erated to exclude the line signal devices from operative relation with the lines.

l2. A telephone system including al plurality of telephone lines extending' from substations to a central office, signal receivers :and the inducing Winding, and line signal devices individual to the telephone lines, said magnet being common to said lines and also serving as a common line signal.

3. A telephone system including a plurality of telephone lines extending from substations to a central oflice, signal receivers at the substations, an induced or secondary Winding at the central oiiice, an inducing Winding at the central oiiice, a circuit making and breaking magnet for interrupting current flowing through the inducing Winding, switchinglnechanism at the central ofce for bringing said induced Winding into operative relation With aline to be called and the signal receiver at the substation thereof and` for closing circuit through said magnet and the inducing Winding, and means whereby a substation calling party may operate said magnet as a line slgnal.

In Witness whereof, I hereunto subscribe my name this 12th day of October A. D., 1909.

GEORGE c. cuMMiNes.

Witnesses:

L. Gr. STROH', G. L. CRAGG. 

